For example, a rotary machine capable of extracting mechanical energy from kinetic energy of a fluid is known.
As the rotary machine, a turbocharger, an expander, a gas turbine, or the like is known, and a radial turbine, a mixed flow turbine, or the like is provided in these.
In general, as the turbocharger, a variable capacity turbine is used, which has a function which regulates a flow rate of an exhaust gas serving as a working fluid according to a change of output of an engine.
In addition, in a case where an expander is used in an apparatus which converts exhaust energy into electric energy, it is necessary to change output while maintaining a constant rotating speed in order to maintain a constant generation frequency. The expander has the above-described variable capacity function in order to cope with the above-described circumstances.
In addition, since a gas turbine used in a jet engine or the like is provided to accelerate or decelerate an aircraft, the gas turbine also has the variable capacity function.
Meanwhile, in order to realize the variable capacity function of the turbocharger, currently, various technologies are known. For example, there is a technology (for example, PTL 1) which changes a throat area by regulating an attachment angle of a nozzle, a technology which uses a flow regulating valve or a bypass valve, or the like.
Here, FIG. 11 shows a turbine having a variable capacity function which uses a nozzle in the related art. In order to exert the variable capacity function, a turbine 100 includes an on-off valve 101 which is provided on an upstream end of a division wall 102 of a a scroll flow path C0 and regulates a flow rate of a working fluid F0 flowing in a turbine rotor blade 103 by rotating the on-off valve 101 with the upstream end as a supporting point.